Polyphenylene ether blends and a process for the preparation thereof

ABSTRACT

The present invention concerns polymer blends and processes for the preparation thereof. The present blends contain a) 5 to 95 parts by weight of poly(2,6-dimethyl-1,4-phenylene)ether, b) 95 to 5 parts by weight of a second polymer which is immiscible therewith, and c) a component (a compatibilizer) which enhances the compatibility of the polymers. According to the invention the component enhancing the compatibility of the polymers comprises 0.1 to 10%, preferably about 1.5 to 10%, calculated on basis of the total weight of components a and b, of at least one compound C, which has the formula 
     
         A.sub.i --B.sub.j                                          I 
    
     wherein 
     A stands for a group which contains at least one ring with 3 to 7 members, capable of forming ring-to-ring interactions with the phenyl rings of poly(2,6-dimethyl-1,4-phenylene)ether, 
     B is a polar group, 
     i is an integer 1 to 20, and 
     j is an integer 0 to 20, 
     whereat 
     i+j is greater than or equal to 2, 
     the melting point of compound C is above 50° C. and the boiling point thereof above 200° C. (at 760 mmHg) and c 
     compound C is capable of at least partially dissolving poly(2,6-dimethyl-1,4-phenylene)ether and is preferably a hydroquinone derivative.

BACKGROUND OF THE INVENTION

The present invention concerns a polymer blend which is useful forproducing fibers, coatings and films.

Such a blend generally comprises 5 to 95 parts by weight ofpoly(2,6-dimethyl-1,4-phenylene) ether, 95 to 5 parts by weight of apolymer other than polyamide, which is immiscible therewith, and acomponent (a compatibilizer) which enhances the compatibility of saidpolymers.

The invention also concerns a process for the preparation of novelpolymer blends and new products containing said blends.

Poly(2,6-dimethyl-1,4-phenylene) ether (PPE) is formed by alternatingmethyl-substituted phenyl rings and ether groups. PPE is an almostamorphous thermoplastic polymer. Its glass transition temperature(T_(g)) is generally in the range from 205 to 210° C. Its degree ofcrystallinity is typically a few percent. The melting point of thecrystals is in the range from 262 to 267° C. (Polym. Prepr. 1971, 12,317). It should be pointed out that a particular advantage of PPE liesin the fact that the polymer behaves plastically at very lowtemperatures, even at -200° C. The heat resistance of PPE is high (HDT/A174° C.).

Since PPE is very aromatic it is also rather rigid. Therefore, PPE is aninteresting polymeric blending component for providing stiffness and forincreasing strength. However, the melt index of PPE is very high; inother words, it is almost impossible to process it by using traditionalpolymer melt processing techniques, such as injection moulding orextrusion. Because of the high melt viscosity, the processingtemperature should be increased over 300° C., at which temperature itbecomes difficult to blend the polymer with other polymers which havelower melting points. Furthermore, even in oxygen-free conditions, PPEis thermally stable only at temperatures of up to about 250° C., andwhen the temperature is raised over 300° C. gelling will be initiated.

It is known in the art that the viscosity of polymers can generally belowered by using plasticizers. Plasticizers can also be used to improveprocessibility, flexibility and elasticity (ASTM D 833). Proper actionof the plasticizer requires that the polymer and the plasticizer besufficiently miscible with each other. Generally, the plasticizer shouldbe soluble in the polymer which is to be plasticized or vice versa. Eachpolymer has its own specific plasticizer, because dissolution depends onthe chemical compatibility of the polymer which is to be plasticized andthe dissolving admixture.

It is also known in the art that when a very small amount of aplasticizer is used, which is completely miscible with the polymer, itis possible to increase the stiffness, strength and toughness of thepolymer. This phenomenon is called "antiplasticizing". Generally, saidphenomenon and its basis for polymers have been described extensively inthe literature (Adv. Chem Ser., 48, 185 (1965), J. Appl. Polym. Sci.,11, 211 (1967), J. Appl. Polym. Sci., 11, 227 (1967), J. Macromol.Sci.-Phys., B1, 433 (1967), Polym. Eng. Sci., 9, 277 (1969), J. Polym.Sci. Polym. Lett. Ed., 7, 35 (1969), Polym. J. 4, 23 (1973), Polym. J.,4, 143 (1973), J. Macromol. Sci.,-Phys., B14, 251 (1977), J. Pol. Sci.,J. Appl. Poly. Sci., 23, 1935 (1979), J. Appl. Poly. Sci., 11, 2553(1967), J. Appl. Poly. Sci., 17, 2173 (1973), J. Appl. Phys., 43,4318,(1972), A. Bondi, Physical Properties of molecular Crystals, Liquids andGlasses, Wiley, 1968, J. Polym. Sci. Polym. Lett. Ed., 21, 1041 (1983),ACS Symp. Ser., 223, 89 (1983), J. Pol. Sci., Part B, 25, 957 (1987), J.Pol. Sci., Part B. 25, 981 (1987), J. Pol. Sci., Part B, 25, 1005(1987), Macromolecules 21, 1470 (1988)). Said publications deal with theinfluence of the admixture on the mechanical properties, volume andglass transition of the polymer, but they do not address, for example,the influence of the admixture on the compatibility of the polymer withanother polymer.

PPE is conventionally made processible by using a polymer, viz.polystyrene, as plasticizer. Polystyrene is blended with PPE, which ismiscible with polystyrene at all mixing ratios. The properties of thePPE/PS-blend so formed can be controlled by adjusting the mixing ratios.Polystyrene lowers the viscosity of the PPE and improves the flowproperties of the polymer blend. PPE is in a corresponding way at leastpartially miscible with and soluble in polymers which are similar topolystyrene, such as isotactic polystyrene, poly(p-methylstyrene),poly(α-methylstyrene), copolymers of halostyrene and styrene,poly(2-methyl-6-phenyl-1,4-phenylene) ether, andpoly(2-methyl-6-benzyl-1,4-phenylene) ether.

Plasticizing of PPE with high impact polystyrene (HIPS) produces ablend, which, due to its impact strength and other properties, is ofgreat importance as a structural polymer material in components used inthe automotive industry and in the industry producing electricalappliances. PPE/HIPS blends are processible by conventional meltprocessing methods. The proportion of HIPS in the blends can vary widelydepending on the specific application. However, it is often 50 to 80wt-%. Stiffness and tensile strength decrease as the concentration ofHIPS increases, as will be shown in an example given below. When theproportion of HIPS is diminished, the processing of the polymer blendbecomes more difficult.

U.S. Pat. No. 4,826,919 teaches further improvement of the flowproperties of PPE/HIPS blends by using small amounts of triphenylphosphate, mineral oil, silicon oil and polyolefins. However, themechanical properties, such as the impact strength, tensile strength andheat resistance, are impaired by such additions.

The prior art, J. Pol. Sci., Part B, 25, 957 (1987), J. Pol. Sci., PartB, 25, 981 (1987), J. Pol. Sci., Part B, 25, 1005 (1987), Macromolecules21, 1470 (1988), also teaches plasticizing PPE by using oligomericplasticizers. These substances have been exemplified by tricresylphosphate, Kronitex 50 (an organic phosphate), di-2-ethylhexylphthalate, dioctyl sebacate, dimethyl sebacate, and dibutyl sebacate.Said plasticizers will lower the glass point while, at the same time,the stiffness is impaired at room temperature or temperatures abovethat. In other words, said oligomeric admixtures act in the same way asconventional plasticizers; no essential stiffening or antiplasticizinghas been noticed at said conditions.

In addition to the blends formed by PPE and polymers miscible with it,in particular polystyrene, it is known that PPE can be blended withpolymers which are immiscible with it. Thus, polyamide 6 (PA6) can beused in amounts of 1 to 6 wt-% for improving the flow properties of PPE.On a molecular level, however, polyamide and PPE do not form miscibleblends. The prior art methods for preparing PPE/PA blends are thereforebased on grafting PPE with maleic anhydride, which reacts with theterminal amine groups of the polyamide. (Campbell, J. R., Pol. Eng. Sci.Vol. 30(1990) No. 17, 1056). Blends of PPE and PA are used particularlyin the automotive industry for applications requiring good chemicalstability.

PPE blends with polyolefins have been compatibilized with, for instance,di-block copolymers of saturated styrene and butadiene (EP 0 358 993) orwith polypropylene grafted with polystyrene (EP 0 352 057 and EP 0449087). Polymers containing glycidyl methacrylate or maleic anhydride areknown to be used for compatibilizing PPE-blends. The aforementionedfunctional groups can react with the terminal hydroxy groups of PPE (EP0 356 194 and DE 39 26 292).

The prior art also includes teachings of PPE blends formed withpolyesters. Polymer 32 (1991) pp. 2150-2154 discloses a complex blendingcombination, wherein PPE, poly(butylene terephthalate) (PBT),polycarbonate (PC) and a triblock polymer of styrene-ethylenebutylene-styrene (SEBS) form a structure, in which PBT is the continuousphase, PPE is modified with the SEBS-elastomer and polycarbonate ispresent at the interface between the PPE and the PBT.

Furthermore, Polymer 33 (1992) pp. 4322-4330 discloses how aromaticliquid crystalline polymers (LCP) can be used for improving the flowproperties of PPE. LCP is not miscible with PPE, but the low meltviscosity of the LCP at high temperatures allows for processing of thePPE. However, the immiscibility gives rise to poor adhesion between thephases. The mechanical properties are therefore not good.

Several oligomeric solvents for PPE are known in the art: benzene,toluene, ethylbenzene, chlorobenzene, chloroform, carbon tetrachloride,trichloroethylene and dichloromethane (Polymer, Vol. 28 (1987), 2085).Decaline has also been suggested as a solvent for PPE (Janeczek, H.,Polymer, 19 (1987) January, 85). Furthermore, α-pinene has beenmentioned. With the help of some of the above mentioned solvents,partial crystallization of the PPE can be achieved.

PPE is generally only partially soluble in aliphatic hydrocarbons,acetone, several alcohols and tetrahydrofurane. PPE exhibits goodresistance against water, acids and alkalis. (Kroschwitz, HighPerformance Polymers and Composites, John Wiley & Sons 1991, U.S.A). Ahomogeneous miscible mixture is obtained from toluene and PPE by keepingthe proportion of PPE at a maximum of 40 wt-%, when the temperature israised to 110° C. When the mixture is cooled, some crystallization ofthe solvent and PPE can possibly be observed (J. Pol. Sci. Pol. Phys.Ed. Vol. 15 (1977) 167).

A homogeneous solution of PPE and methylene chloride can be prepared atroom temperature by keeping the concentration at a maximum of 20 wt-%.Bromochloromethane and ethylene bromide and α-pinene and cis- andtrans-decaline have also been mentioned as solvents for PPE which caninduce crystallization (Pol. Letters, Vol.7 (1969), 205).

In summary, it can be stated on basis of the prior art that it ispossible to obtain mechanically satisfying blends of PPE with otherpolymers

primarily by using polystyrene and derivatives thereof,

by using block polymers containing styrene as compatibilizers for, e.g.,polyolefins,

by utilizing terminal group chemistry, PPE being chemically modifiedwith an active group, which reacts with the other polymer, or

by utilizing the reactivity of the terminal groups of PPE.

Plasticizing of PPE by using oligomeric additives and their influence onthe mechanical and physical properties as well as on gas permeabilityhave been studied in the prior art.

The fact that PPE is easily miscible with polystyrene and itsderivatives is primarily caused by the formation of a miscible blend.But if PPE is blended with other polymers (which are immiscible withit), such as with polyethylene, according to the prior art theproperties of the blends are generally not good, the mechanical strengthremains poor and the components of the blends are stronglyphase-separated.

For the above reasons there has already for a long time existed a needin polymer technology for providing a way of generally compatibilizingPPE with any matrix polymer, in particular in cases when the miscibilityof PPE with a polystyrene block cannot be relied upon.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a novelsolution for plasticizing PPE so that it can be processed together withpolymers which are immiscible with it, in order to provide novelPPE-based polymer blends.

The present invention is based on the discovery of specific aromatic oralicyclic interface active substances which surprisingly simultaneouslyachieve three desired properties: i) they will make PPE processible, ii)they will increase the stiffness of PPE, and iii) they will work asinterfacially active substances in respect to other polymers in blends.

Polymer blends according to the invention, which contain the componentsmentioned in the introduction, therefore have as a component enhancingthe compatibility of the polymers 0.1 to 10%, calculated on basis of thetotal weight of the PPE and the immiscible polymer, of a compound C withthe formula

    A.sub.i --B.sub.j                                          (I)

wherein:

A is a group which contains at least one 3- to 7-membered ring groupcapable of forming ring-to-ring interactions with the phenyl rings ofthe poly(2,6-dimethyl-1,4-phenylene) ether,

B is a polar group,

i is an integer 1 to 20, and

j is an integer 0 to 20,

provided that

the sum of i and j is equal to or greater than 2;

the melting point of compound C is over 50° C. and its boiling point isover 200° C. (at 760 mmHg) and

compound C is capable of at least partially dissolvingpoly(2,6-dimethyl-1,4-phenylene) ether.

In connection with the invention it has been found that PPE dissolves inthe above-mentioned cyclic compounds sufficiently rapidly, in comparisonto melt processing, as long as the melting temperature is high enough.Thus, 200° C. is an absolute lower limit, the upper limit typicallybeing about 270° C., preferably about 250° C. In other words: anessential prerequisite for dissolution is cyclic structure andsufficiently high temperature. Then the boiling point of the cycliccompound becomes essential. If the substance in itself does not containpolar interactions, its boiling point is low. Therefore, the cycliccompounds according to the invention should contain a polar group whichincreases the temperature of the cyclic compound so that it becomessuitable for blending.

By means of the invention it becomes possible to produce materials,fibres, coatings, films and similar products from blends of PPE andmodified PPE with polymers immiscible therewith.

In connection with the present invention the term "capable of at leastpartially dissolving PPE" indicates that the blend formed from PPE and acyclic compound is essentially homogeneous. Then, the PPE and cycliccompound phases are not distinguishable microscopically.

The term "PPE-product" covers PPE, modified PPE polymers and blends ofPPE with other polymers.

The blends according to the present invention typically comprise thefollowing components:

i) A PPE phase,

ii) One or more substituted solid oligomeric aromatic or alicycliccompounds, which dissolve PPE due to ring-to-ring interaction and whichprovides improved processibility of PPE and increases stiffness thereof,i.e., it works as an antiplasticizer and an interfacially activesubstance in relation to the organic substrate,

iii) One or more organic substrate phases, which do not comprisepolyamide.

iv) Other additives, if any.

Within the scope of the present invention it has been found that

PPE can be antiplasticized by using said substituted aromatic oralicyclic additives,

said antiplasticizing provides an increased stiffness of the PPE at thesame time as its processibility is improved,

and, in particular, it has been found that

said substituted aromatic or alicyclic additives can be functionalizedso that they simultaneously antiplasticize PPE and work as interfaciallyactive additives, i.e. compatibilizers, towards the organic substratephase. Said additives will improve the properties of the blend.

Aromatic compounds have already been used in the prior art forcompatibilization of blends formed by PPE and polystyrene or polyamide,respectively. The suggested solutions are based on the fact, which hasbeen disclosed in, for example, U.S. Pat. No. 3,379,792, viz. that theprocessibility of PPE can be improved by adding 0.1 to 25 wt-% of apolyamide phase. But if the weight ratio of the polyamide is increasedabove 20 wt-%, the PPE and polyamide phases become phase-separated,which leads to a significant deterioration of the mechanical properties.In order to eliminate this problem several alternative solutionsspecific for the compatibilization of polyamides and PPE have beensuggested in the patent literature.

Thus, U.S. Pat. No. 4,659,763 describes the use of cyclic conjugateddiketones for compatibilization of PPE/PA mixtures. The technical effectdisclosed in the publication may be related to the fact that saidketones will achieve formation of grafted copolymers of PPE with thepolyamides. Alternatively, if no actual chemical bonds are formed, itwould appear that the disclosed effect is due to suitable secondaryinteractions. In both cases it is obvious to a person skilled in the artthat the suggested compatibilization method is not applicable as suchfor compatibilization of PPE and other matrix polymers except for thepolyamides. It should be pointed out that compatibilization based onchemical reactions requires chemistry tailor-made for each matrixpolymer and admixtures selected on basis of such chemistry. Also thespecific interactions of the second alternative are typical for eachpolymer-polymer-pair or polymer-admixture-pair and even seemingly smallchanges can lead to big differences in the properties. This is evidencedby the fact that most polymers are not miscible with each other.

Therefore, U.S. Pat. No. 4,659,763 does not provide a general method forcompatibilization of PPE with other polymers, such as polyolefins orpolyesters, in particular with liquid crystalline polyesters. It must benoted that polyamides/polyolefins and polyamides/liquid crystallinepolyesters form immiscible, phase-separated pairs, which shows that saidpolymers of both the exemplified pairs are different by character.

In summary, it can be stated that even if U.S. Pat. No. 4,659,763suggests a method for compatibilizing PPE with polyamides, no teachingis provided regarding admixtures or methods that can be used forcompatibilizing PPE generally with any polymer, such as a polyolefin orpolyester.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows the viscosities of PPE/tbHQ 95/5- and 90/10-blends as afunction of the shearing rate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The PPE Phase

As the following description will show, it is essential for the presentinvention that PPE contains aromatic rings. It is therefore obvious to aperson skilled in the art that the terminal groups of PPE can bemodified while still retaining essentially the same properties asregards dissolution, antiplasticization and compatibilization of thepolymer in the solvents mentioned in the present invention.

The Cyclic Phase

The substituted aromatic or alicyclic phase is the decisive feature ofthe present invention. Said admixture or additive is used in the presentinvention for two unique purposes: i) as an antiplasticizing agent forproviding processibility of PPE and for improving the mechanicalproperties thereof, and ii) as a component of interfacial activitytowards the organic substrate phase.

As mentioned above, the admixture is used in amounts of about 0.1 to 10wt-%, a particularly preferred concentration range being about 1.5 to 10wt-%. In small amounts (less than 1%) the admixture mainly acts as astabilizing agent.

The antiplasticization will manifest itself as, e.g., a lowering of theglass transition temperature as a function of the mixing ratios. Themelt viscosity of the PPE will decrease, which can be determined forexample by measuring the viscosity with a capillary rheometer. It istherefore possible to make PPE processible by conventional meltprocessing at temperatures below 300° C., preferably below 270° C.

In contrast to normal plasticization of polymers by using plasticizers,the most important property of the invention is the compatibilizationachieved by the admixture. This term signifies a regulation of theinterfacial energy of the PPE and the organic substrate phase. Accordingto the invention, the part of the formula A_(i) --B_(j), which interactswith the PPE, is part A, that is one or several aromatic or alicyclic orheterocyclic rings, which interact with the phenyl rings of PPE byring-to-ring interaction. This interaction is constituted by van derWaals interaction and its magnitude is typically about 5 to 10 kcal/mol.

Part A can contain 1 to 20 ring structures, but preferably the cycliccompound used is oligomeric, which in this context means that itcontains a maximum of 8 to 10 ring groups.

In the above formula each A preferably comprises a substituted 3-, 4-,5-, 6- and 7-membered aromatic or alicyclic ring, which optionallyincludes one or several divalent nitrogen, sulphur or oxygen atom(s).Part A then comprises a ring group with at least two rings, for exampletwo fused rings.

Part A is preferably substituted so that it fits together with theorganic substrate phase. This functionality is selected depending on thestructure of the substrate phase. Thus, for a non-polar polymer, such aspolyethylene, a non-polar functionality should be chosen, such as analkyl, alkenyl, cycloalkyl or phenyl group or a similar group. Togetherwith a polar polymer a polar group should be chosen instead, forexample: --OH, --COOH, --COO--, --CO--, --NH₂ --, --NH--, SO₂ --,--SH,--S--, SO₂ NH₂ --, CONH₂, --NHCO--, --PO₃ --, --NO₂, --CN, --CON═, thehalogens --F, --Cl, --Br, and --I or a similar group.

Part B preferably comprises a polar group, which gives the cycliccompound a sufficiently high boiling point, i.e. at least over 200° C.,preferably over 250° C. and in particular over 270° C. The polar groupcan be any of the above mentioned polar groups.

Preferred groups of compounds are those compounds, wherein each group offormula (I) is independently a sulphonamide, phenol, benzoic acid,aniline or benzamide, which is substituted by one, two or threesubstituents independently comprising --H, --OH, --COOH, alkyl, alkenyl,alkoxy, alkanoyl, alkylthio, alkylthioalkyl, alkyl amide,alkylamidealkyl, alkyl hydroxy, alkyl carboxyl, having from 1 to aboutat least 20 carbon atoms; or alkylaryl, arylalkyl, alkylsulphinyl,alkoxyalkyl, alkylsulphonyl, alkoxycarbonyl, wherein the alkyl or alkoxyhas from 0 to about 20 carbon atoms; or alkyl having from 1 to about 20carbon atoms; or an alkyl with 1 to about 20 carbon atoms and whereintwo substituents together may form a 2-, 3-, 4-, 5-, 6- or 7-memberedaromatic or alicyclic ring, which ring may optionally include a divalentnitrogen, sulphur or oxygen atom; or a branched tertiary alkyl, having acarbon chain of from 1 to about 20 carbon atoms; or a polar group, suchas --NO₂, or --CN; or a halogen, such as --F, --Cl, --Br, and --I.

Particularly preferred groups of formula (I) are

phenylphenol, naphthol, cyclohexanephenol, aminophenol,

dihydroxybenzene, dihydroxynaphthalene, alkylhydroxybenzoate,hydroxyalkylphenone, hydroxyalkyl ether, hydroxyalkylbenzamide,

hydroxyalkoxy benzaldehyde, dihydroxybenzoic acid, dialkoxybenzoic acid,alkyl gallate, hydroxydiphenylmethane, phenylsulphoxide, phenylsulphone,phenyldihydroxybenzene, biphenol, bisphenol, hydroxybenzophenone,benzophenone, phenylbenzene-dicarboxylic acid, dihydroxybenzophenone,trihydroxybenzophenone;

aminoalkylamide, alkylaminobenzoate, alkylaminobenzaldehyde,dialkylaminobenzaldehyde, phenyidiamine, hydroxybenzamide,alkoxyaniline;

benzoic acid, alkoxybenzoic acid, benzenedicarboxylic acidalkylmonoester;

dicarboxylic acid alkyldiester, dicarboxylic acid diamide, trimellitate;

benzene carboxylic acid or hydroxybenzoic acid.

Particularly preferred compounds are t-butyl hydroquinone, (in position3) thioalkylated hydroquinones, and the compounds of the followingformula: ##STR1## Organic Substrate Phase

This phase comprises either a polymer or a prepolymer or a mixturethereof and it is in a fluidized state during blending.

Except for polyamide the polymer matrix can comprise any suitablepolymer material which has the desired properties regarding strength andprocessability. It can be a thermosetting plastic or a thermoplastic.

As examples of suitable polymers, the following may be mentioned:polyolefins, polyesters and polyether. Suitable polyolefins arerepresented by polyethylene, polypropylene, polybutylene,polyisobutylene, poly(4-methyl-1-pentylene), including copolymers ofethylene and propylene (EPM, EPDM) and chlorinated (PVC) andchlorosulphonated polyethylenes. The polymer substrate may alsocomprises the corresponding polyalkanes, which contain styrene (PS),acryl, vinyl and fluoroethylene groups, and different polyesters, suchas poly(ethylene terephthalate), poly(butylene terephthalate) andpolycarbonate, polyamides and polyethers (e.g. poly(phenylene ether).Particularly preferred polymers are the polyolefins and polyesters.

The organic substrate phase may also contain a liquid crystallinepolymer (or it may consist of such a polymer).

The liquid crystalline polymer may, for instance, comprise an aromaticmain chain thermotropic polymer, preferably a thermotropic polyester,poly(ester amide), poly(ester ether), poly(ester carbonate) orpoly(ester imide). It can also comprise a copolymer of a polyester, suchas a copolymer of poly(ethylene terephthalate) and hydroxybenzoic acidor a copolymer of hydroxynaphthoic acid and hydroxybenzoic acid.

Generally, the liquid crystalline polymer, which is used in the presentinvention, can be defined as a polymer which is formed when thecomponents following general formulas (or at least two of them) arereacted with each other: a dicarboxylic acid of formula (II)

    HOOC--R.sub.1 --COOH                                       (II)

a diol of formula (III)

    HO--R.sub.2 --OH                                           (III)

a hydroxycarboxylic acid of formula (IV)

    HO--R.sub.3 --COOH                                         (IV)

wherein

R₁, R₂, and R₃ each independently represents a bivalent aromatichydrocarbon group,

a group of formula R₄ --X--R₅, wherein R₄ and R₅ represent a bivalenthydrocarbon group and X is an oxygen or a sulphur atom, a sulphonyl,carbonyl, alkylene, or ester group or X is a single bond,

a xylylene group or

a bivalent aliphatic hydrocarbon group.

The liquid crystalline polymer can also comprise a homopolymer of ahydroxycarboxylic acid of formula (V)

    HO--R.sub.3 --COOH                                         (V).

Typically, the aromatic dicarboxylic acids of formula (II) compriseterephthalic acid, isophthalic acid, 4,4'diphenyl-dicarboxylic acid,diphenyl ether-4,4'-dicarboxylic acid, diphenylethane-3,3'-dicarboxylicacid, diphenylethane-4,4'-dicarboxylic acid, diphenylether-3,3'-dicarboxylic acid, 4,4'-triphenyl-dicarboxylic acid,2,6-naphthalenedicarboxylic acid,diphenoxyethane-4,4'-dicarboxylic-acid,diphenoxybutane-4,4'-dicarboxylicacid, diphenoxyethane-3,3'-dicarboxylic-acid, andnaphthalene--1,6-dicarboxylic acid.

Said aromatic dicarboxylic acids may be alkyl-, alkoxy-, orhalogen-substituted. The substituted derivatives comprisechloroterephthalic acid, dichloroterephthalic acid, bromoterephthalicacid, methylterephthalic acid, dimethylterephthalic acid,ethylterephthalic acid, methoxyterephthalic acid, and ethoxyterephthalicacid.

The alicyclic dicarboxylic acids of formula (II) comprisetrans-1,4-cyclohexanedicarboxylic acid, cis-1,4-cyclo-hexanedicarboxylicacid, and 1,3-cyclohexanedicarboxylic acid.

The alicyclic dicarboxylic acids may also be substituted by one or morealkyl-, alkoxy-, or halogen-substituent(s). The substituted dicarboxylicacid derivatives comprise trans-1,4-(1-methyl)-cyclohexane-dicarboxylicacid and trans-1,4-(1-chloro)cyclohexane-dicarboxylic acid.

The aromatic diols of formula (III) comprise hydroquinone, resorcinol,4,4'-dihydroxydiphenyl, 4-4'-dihydroxytriphenyl, 1,6-naphthalenediol,2,6-naphalene-diol, 4,4'-dihydroxydiphenyl ether,3,3'-dihydroxydiphenyl, 1,1-bis(4-hydroxyphenyl)-methane,bis(4-hydroxyphenoxy)-ethane, 2,2-bis(4-hydroxyphenyl)propane, and3,3'-dihydroxy-diphenyl ether. These diols may be substituted by one ormore alkyl-, alkoxy-, or halogen substituent(s), which derivatives areexemplified by the following list: chlorohydroquinone,methylhydroquinone, 1-butyl hydroquinone, phenylhydroquinone,methoxy-hydroquinone, phenoxyhydroquinone, 4-chlororesorcinol, andmethylresorcinol.

Typical examples of alicyclic diols of formula (III) include trans- andcis-1,4-cyclohexanediols, trans-1,4-cyclohexane-dimethanol,trans-1,3-cyclohexanediol, cis- 1,2-cyclohexanediol, and trans-1,3-cyclohexanedimethanol.

Instead of these compounds the corresponding alkyl-, alkoxy-, orhalogen-substituted derivatives can be used, as well.

The aliphatic diols of formula (III) can be straight-chained or branchedand comprise ethylene glycol, 1,3-propanediol, 1,4-butanediol, andneopentyl glycol.

The aromatic hydroxycarboxylic acids of formula (IV) comprise4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoicacid, and 6-hydroxy-1-naphthoic acid. These compounds can be alkyl-,alkoxy-, or halogen-substituted. The substituted aromatichydroxycarboxylic acid derivatives preferably comprise3-methyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid,2,6-dimethyl-4-hydroxybenzoic acid, 3-methoxy-4-hydroxy-benzoic acid,3,5-dimethoxy-4-hydroxybenzoic acid, 6-hydroxy-5-methyl-2-naphthoicacid, 6-hydroxy-5-methoxy-2-naphthoic acid, 3-chloro-4-hydroxybenzoicacid, 2,3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-hydroxybenzoicacid, 2,5-dichloro-4-hydroxybenzoic acid, 3-bromo-4-hydroxybenzoic acid,6-hydroxy-5-chloro-2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoicacid, and 6-hydroxy-5,7-dichloro--2-naphthoic acid.

In addition to the above mentioned polyesters, the LC-polymers used inthe invention can comprise the corresponding polyester amides. It isalso possible to use polymers having a main chain containing conjugateddouble bonds, the monomer units of said main chain being linked tounsubstituted or substituted side chains which, together with the mainchain render the polymer liquid-crystal properties. Examples of suchpolymers are polytiophene, polyaniline, polyacetylene, polypyrrole andpolyparaphenylene substituted with alkyl chains containing at least 8carbon atoms.

Particularly preferred liquid crystalline polymers are represented bythe copolymer of poly(hydroxy benzoate) and hydroxy naphthoic acid andpoly(ester imide), the latter being described in more detail in WOPublished Patent Application No. 94/06846. Poly(ester imide)s andseveral other main chain liquid crystalline polymers and PPE arestructurally similar and fit well together, which makes it possible toreplace a part of the PPE with a poly(ester imide). Alternatively, thepoly(ester imide) can be used even in small amounts to improve thestrength properties of PPE (i.e. the poly(ester imide) can be used forPPE upgrading).

The molecular weights of the preferred thermoplastic polymers areusually in a range from about 5,000 to 50,000, preferably about 10,000to 30,000. The flexural modulus (0.5-0.25%) of the matrix polymer ispreferably about 100-10,000 MPa, in particular about 500-5,000 MPa.

Other Potential Admixtures

It is clear to a person skilled in the art that said mixture can becomplemented with admixtures comprising inert, solid fillers, such astalc, carbon black or corresponding fillers, or with fibrous admixtures,such as glass fibres, carbon fibres or organic fibres. It is furtherobvious to a person skilled in the art that stabilizing agents andsimilar agents, which do not essentially affect the effect of thepresent invention, can be added to the mixture.

Preparation and Processing of the Polymer Blends

The blends according to the invention are prepared by mixing togetherthe components of the polymer blend at a temperature in the range from200 to about 270° C. Desired end products can be formed from themixtures in manners known per se. Generally the components of thepolymer blend are first mixed together to form a blend, to whichadmixtures and adjuvants are optionally added. Then the polymers arecompounded by melt processing. Applicable blending processes includebatch and continuous processes. Preferably single- or twin-screwextruders are used for compounding PPE with thermoplastics.

The blends according to the invention are processed by methods known perse in polymer technology for preparing the final products.

Considerable advantages are obtained by the invention. Thus, by blendingPPE with other polymers using as admixtures or compatibilizers cyclicsolid compounds which have a functional group which fits in with theother polymers, blends are obtained which have advantageous mechanicaland thermal properties. These compounds, which plasticize PPE, alsoincrease the stiffness and tensile strength of PPE, promote its meltprocessing (which is partially due to the lowered viscosity of the PPE)and improve the morphology thereof. The structure of the polymer blendsbecomes more homogeneous and the stiffness and tensile strength areimproved by the addition of the compatibilizers.

The modulus of elasticity is at least 10% greater than for polymerblends which do not contain component C, which has instead been replacedby the corresponding amount of component b.

The general method disclosed in the present invention makes it possibleto adjust the properties of PPE blends for each specific application byselecting one or more suitable matrix polymers, one or morecompatibilizers which fit with it and with PPE, and furthermore,possibly, a solid non-melting admixture, such as talc or glass fibre andto optimize the proportions of the aforementioned components accordingto the set requirements.

Further advantages and features of the invention will appear from thefollowing working examples.

EXAMPLES

Example A (comparative example) shows that the method of plasticizingPPE is critical when good mechanical properties are sought.

Example 1 discloses some cyclic substances which lower the glasstransition point of PPE. Aromatic compounds with a melting point above50° C. and a high boiling point, which preferably is over 200° C., inparticular over 250° C., have been studied by determining theirinfluence on the glass transition point of PPE. It is commonly knownthat if there is a strong interaction between two organic compounds thentheir glass transition temperatures will shift closer towards eachother. In particular, if two components are completely miscible on amolecular level, they will only have one common glass transitiontemperature.

Example 2 shows that the miscibility of PPE and tert-butyl hydroquinoneis not a phenomenon which will appear at certain temperatures only.

Example 3 is a counter example for Example 1.

Example 4 indicates that tert-butyl hydroquinone will function as aplasticizer for PPE at various mixing ratios. Dissolution and a decreaseof viscosity and also an increase in the stiffness of PPE can be noticedas the amount of tert-butyl hydroquinone is increased.

Example 5 shows at one mixing ratio that hydroquinone will work in thesame way as a plasticizer for PPE.

In Example 6 it has been found that tert-butyl hydroquinone works as acompatibilizer in blends of PPE and HDPE. As the amount of thetert-butyl hydroquinone increases, the stiffness and the tensilestrength of the blends will increase.

Example 7 shows that decyl hydroquinone works in a corresponding way inPPE/HDPE blends as tert-butyl hydroquinone in an experiment carried outat one mixing ratio.

Example 8 shows that tert-butyl hydroquinone works as a compatibilizerbetween PPE and an LCP. The LCP used in the example is a copolymer ofhydroxynaphthoic acid and hydroxybenzoic acid.

Example 9 concerns the preparation of blends based on PPE and poly(esterimide)s.

Example A (Comparative Example)

PPE (supplied by Research Institute of Macromolecular Chemistry) wasplasticized using high impact polystyrene HIPS (Neste SB 735). Theamount of HIPS varied from 30 wt-% to 80 wt-%, the minimum value beingset by technical limitations of the apparatus used: the smaller theamount of HIPS the more difficult the melt processing. Said binarymixture was blended in a Berstorff ZE 25 twin-screw mixer at atemperature of 270° C. using a rotation speed of 300 rpm. A blendconsisting of 50 weight-% PPE and 50 weight-% HIPS was plasticized toform one phase, which had a glass point of 141.6° C., a modulus ofelasticity of 2.53 GPa, a tensile strength of 63 MPa, an elongation atbreak of 21%, a notched Charpy impact resistance (at 23° C.) of 10.6kJ/m² and a notched Charpy impact resistance (at -40° C.) of 4.5 kJ/m².In other words the plasticized PPE had rather a good impact toleranceand was rather stiff.

Under the same conditions, 25 weight-% PPE, 25 weight-% HIPS and 50weight-% polypropylene (PP) (Neste VC 12 12 H) were mixed. The blendprepared had a modulus of elasticity of 1.64 GPa, a tensile strength of20.3 MPa, an elongation at break of 2.6%, a notched Charpy impactresistance (at 23° C.) of 1.3 kJ/m², a notched Charpy impact resistance(at -20° C.) of 1.1 kJ/m².

Furthermore, a mixture of 35 weight-% PPE, 35 weight-% HIPS and 30weight-% polypropylene (PP) (Neste VC 12 12 H) was prepared under thesame conditions. The blend had a modulus of elasticity of 1.78 GPa, atensile strength of 24.6 MPa, an elongation at break of 2.4%, a notchedCharpy impact resistance (at 23° C.) of 1.2 kJ/m², a notched Charpyimpact resistance (at -20° C.) of 0.9 kJ/m².

Both PPE/HIPS/PP blends had a morphology characterized by a strongphase-separation. The impact resistance was very poor. Likewise was thestiffness poor. It can be concluded that the way in which theplasticizing and compatibilizing is achieved is essential and criticalto the properties of PPE blends formed with polyolefins.

Example 1

PPE (M_(w) 41,200, M_(n) 21,700, supplied by Asahi Chemicals) was mixedwith different aromatic compounds in a 5 g single-screw mixer operatedbatch-wise using N₂ as protective gas. The mixing temperatures (T) arementioned in Table 1. The mixing time was constantly 30 minutes. The mixwas analyzed by DSC using a scanning rate of 20° C./min. The glasstransition temperatures were determined by DSC. The glass transitiontemperature, T_(g), of pure PPE is 211° C. The analysis results arecollected in Table 1. The results show that the aromatic compounds willprovide a strong decrease of the glass transition temperature of PPE,because they act as solvents for PPE. Only one T_(g) can be observed forall samples, except for those in which the solvents had caused theformation of a crystalline phase. In the latter case, no glasstransition temperature could be observed.

                  TABLE 1    ______________________________________    Blends of PPE and some organic compounds                Ratio of PPE                          T (° C.)    Compound    (weight-%)                          mixing  T.sub.g (° C.)                                         Comments    ______________________________________    Hydroquinone                50        270            crystalline    t-Butyl hydro-                50        270     48    quinone    Resorcinol  50        270     157    Catechol    50        270     142    Bisphenol-A 50        270     136    Phenylhydro-                50        270     126    quinone    2-Phenylphenol                50        270     108    Benzoic acid                50        270     78    4-Hydroxy-  50        270     116    benzophenone    2,4-Dihydro-                50        270     129    benzophenone    3-Hydroxy-  50        270            crystalline,    benzoic acid                         dissolved    Phenyl terephthalic                50        300     192    acid    2-Hydroxy-6-                50        300            crystalline,    naphthoic acid                       dissolved    Benzamide   50        270     60    o,p-Toluene-                50        270            crystalline,    sulphonamide                         dissolved    N-Phenyl-1,4-                50        270     82    phenylene-    diamine    Phenothiazine                50        270            crystalline,                                         dissolved    ______________________________________

Example 2

PPE and tert-butyl hydroquinone were mixed at a mixing ratio of 75/25 ina 5 g single-screw mixer at two temperatures, 300° C. and 200° C., usinga mixing time of 20 minutes in an N₂ protective gas atmosphere. In bothcases, one glass point was obtained at a temperature of 110° C. Bothmixing temperatures produced systems which were miscible on a molecularlevel.

Example 3

(Outside of the Invention)

A non-aromatic solvent which does not dissolve PPE under theexperimental conditions observed.

A mixture of 50 wt-% PPE (Asahi M_(w) 41,200, M_(n) 21,700, produced byAsahi Chemicals) and 50 wt-% stearic acid (Aldrich) was prepared in a 5g single-screw mixer operated batch-wise at a temperature of 270° C.using N₂ as protective gas. The mixing time was 20 min. DSC-analysisshowed that the glass transition temperatures of both components werecompletely separate and unchanged, which indicates that PPE and stearicacid are not miscible on a molecular level. Said aliphatic organiccompounds are not miscible with PPE and do not act as plasticizers forit.

Example 4

PPE and tert-butyl hydroquinone (tbHQ) were mixed at mass ratios of90/10, 95/5 and 97.5/2.5 in a corotating twin-screw extruder BerstorffZE 25 at a temperature of 270° C. using N₂ as a protective gas. Thescrews of the extruder comprised mixing and conveying means arranged ina specific order. The blends were injection moulded and tested accordingto ISO standards for tensile modulus (E), yield strength (σ_(y)) andmaximum elongation (ε_(max)): ISO/R527; flexural modulus (G): ISO 178;Charpy notched impact resistance: ISO 179/1D at +23° C.; and HDT/B: ISO75. Table 2 contains a summary of the test results for the blends.

                  TABLE 2    ______________________________________                                      notched           E       s.sub.y e.sub.max                                G     impact                                            HDT/B T.sub.g    PPE/tbHQ           (GPa)   (MPa)   (%)  (GPa) (kJ/m.sup.2)                                            (° C.)                                                  (° C.)    ______________________________________    97.5/2.5           2.34    80.5    105  2.55  3.5   176   190    95/5   2.56    81.8    41   2.58  3.1   163   175    90/10  2.6     81.9    37   2.63  2.8   142   155    ______________________________________

FIG. 1 contains graphical presentations of the viscosities of the 95/5and 90/10 blends determined by capillary rheometry. The determinationswere made at a temperature of 270° C.

Table 2 and FIG. 1 show that tert-butyl hydroquinone plasticizes PPE. Asa result, the viscosity of PPF decreases so that it becomes readilyprocessible by conventional melt processing methods, such as injectionmoulding or extrusion.

Example 5

Example 4 was repeated by using hydroquinone instead of tert-butylhydroquinone. The weight ratio of PPE to hydroquinone was 95/5. AgainPPE became readily processible. The mechanical properties of the blendare as follows: tensile modulus 2470 MPa, yield strength 71 MPa, maximumelongation 66%, flexible modulus 2470 MPa, notched impact resistance 2.0kJ/m². The glass transition temperature was 181° C. These results showthat hydroquinone also acts as a plasticizer for PPE.

Example 6

HDPE (NCPE 7003, Neste) and PPE (Asahi Chemicals) were mixed in acorotating twin-screw mixer Berstorff ZE 25 at a temperature of 270° C.using N₂ as a protective gas. The blends were dried (at 80° C.overnight) before injection moulding. The injection moulded specimenswere tested according to the ISO standards mentioned in Example 4 afterthey had first been stored for 2 days in a conditioning room. Themechanical properties of the blends are given in Table 3.

                                      TABLE 3    __________________________________________________________________________    Mechanical properties of HDPE/PPE blends                                L-Charpy                                      L-Charpy    PPE HDPE tbHQ                 E   σ                         ε                             G  (kJ/m.sup.2)                                      (kJ/m.sup.2)    (wt %)        (wt %)             (wt %)                 (GPa)                     (MPa)                         (%) (GPa)                                +23° C.                                      +23° C.    __________________________________________________________________________    40  60   --  1.57                     33.1                         4.8 1.56                                6.0   5.0    40  58   2   1.62                     35.0                         6.4 1.62                                5.7   4.7    40  56   4   1.75                     37.9                         4.6 1.68                                7.3   6.8    __________________________________________________________________________

The morphology of the polymer blends was inspected by scanning electronmicroscopy (SEM) at the temperature of liquid nitrogen on a fracturedsurface. The microscopy clearly indicated that without tbHQ, theadhesion and miscibility of HDPE and PPE was poor. The average particlesize of the dispersed phase was over 10 micrometers. When 2.0 wt-% oftert-butyl hydroquinone had been added to the blend, the morphology wasradically changed; the average particle size of the dispersed phase wasnow only 2 to 5 μm on an average. If the amount of the tert-butylhydroquinone was 4 wt-%, the average particle size was only 1 to 3 μm.

It can be concluded that i) tbHQ works as an interfacially active agentbetween PPE and HDPE, ii) it stiffens the blend by antiplasticizing PPE,iii) it increases the impact strength at room temperature and at lowtemperatures and iv) it makes the morphology more homogeneous.

Example 7

The HDPE/PPE blend of Example 6 was repeated by using decyl hydroquinoneinstead of butyl hydroquinone. The decyl hydroquinone was synthesizedfrom decene and hydroquinone by an acid-catalyzed reaction.

The mechanical properties of a blend containing 40 wt-% PPE, 56 wt-%HDPE and 4 wt-% decyl hydroquinone were the following: tensile modulus1670 MPa, yield point 38.4 MPa, maximal elongation 5.3%, flexuralmodulus 1630 MPa, Charpy notched impact resistance 7.0 kJ/m² at +23° C.and 7.7 kJ/m² at -20° C. It can be noted that decyl hydroquinone alsoworks as a compatibilizer in blends of PPE and HDPE on the same basis asin example 6.

Example 8

Blends of PPE (Asahi Chemicals) and an LCP (Vectra A, Hoechst Celanese)were prepared without admixtures and with tert-butyl hydroquinone. Theblends were prepared as described in Example 6 using a meltingtemperature of 290° C. The blends were dried and injection moulded. Themechanical testing was carried out according to the standards listed inExample 4. The properties are indicated in Table 4.

                                      TABLE 4    __________________________________________________________________________    Mechanical properties of PPE/LCP blends                                L-Charpy                                      L-Charpy    PPE LCP  tbHQ                 E   σ                         ε                             G  (kJ/m.sup.2)                                      (kJ/m.sup.2)    (wt %)        (wt %)             (wt %)                 (GPa)                     (MPa)                         (%) (GPa)                                +23° C.                                      +23° C.    __________________________________________________________________________    40  60   --  6.41                     109 2.7 6.56                                29    5.0    40  56   4   7.28                     113 2.3 7.30                                19.4  6.8    __________________________________________________________________________

The results indicate a clear increase of the tensile modulus andflexural strength and tensile strength.

Example 9

Example 8 was repeated using the liquid crystalline polymers of Examples2 and 9, respectively, of WO Published Patent Application No. 94/06846.The amounts of the LCP were in the range of 5 to 95 wt-% and the amountsof the PPE in the range of 95 to 5 wt-%. The first of the LCP's used wasprepared by condensation of trimellite-imide terminated poly(THF) withan acetoxy-terminated trimer of formula HBA-HQ-HBA and withp-acetoxybenzoic acid. The other LCP comprises the corresponding polymerprepared from trimellite-imide terminated silicone.

It can be noticed from the polymer blends that PPE can be replaced evenwith rather large amounts of poly(ester imide) without substantiallyimpairing the strength properties of the polymer. However, already bythe addition of small amounts (5 to 10 wt-%) of poly(ester imide) to theblend, a clear improvement of the tensile modulus and the flexuralstrength and the tensile strength of the PPE can be obtained.

What is claimed is:
 1. A polymer blend comprising:a) 5 to 95 parts byweight of poly(2,6-dimethyl-1,4-phenylene) ether; b) 95 to 5 parts byweight of a second polymer which is immiscible with said ether; and c)0.1 to 10 wt.-%, based on the weight of the ether and second polymer, ofat least one component which enhances the compatibility of the ether ofa) and the polymer of b), said component comprising hydroquinone havinga substituent, wherein the substituent is selected from the groupconsisting of alkyl, alkenyl, alkoxy, alkanoyl, alkylthio,alkylthioalkyl, alkyl amide, alkylamidealkyl, alkyl hydroxy, alkylcarboxyl, having from 1 to about at least 20 carbon atoms; or alkylaryl,arylalkyl, alkylsuphinyl, alkoxyalkyl, alkylsulphonyl, alkoxycarbonyl,wherein the alkyl or alkoxy has up to 20 carbon atoms, or the alkylsubstituent is a branched tertiary alkyl having a carbon chain of from 1to about 20 carbon atoms, or the substituent contains a polar group or ahalogen.
 2. The polymer blend of claim 1 wherein the least one componentis present in the blend in an amount of about 1.5 to 10 wt.-%.
 3. Thepolymer blend of claim 1 wherein the second polymer is a polyolefin. 4.The polymer blend of claim 3 wherein the substituent is alkyl ortert-butyl.
 5. The polymer blend of claim 1 wherein the substituent istert-butyl.
 6. The polymer blend of claim 1 further comprising unmeltedfillers.
 7. The polymer blend of claim 1 wherein the elasticity modulusof the blend is at least 10% greater than that of a polymer blend whichdoes not contain the compatibility enhancing component which has insteadbeen replaced by a corresponding amount of said second polymer.
 8. Afiber comprising a polymer blend according to claim
 1. 9. A coatingcomprising a polymer blend according to claim
 1. 10. A film comprising apolymer blend according to claim
 1. 11. A process for preparing apolymer blend of claim 1, comprising blending together at a temperatureof at least 200° C.a) 5 to 95 parts by weight ofpoly(2,6-dimethyl-1,4-phenylene) ether, b) 95 to 5 parts by weight of asecond polymer which is imnmiscible with said ether, and c) 0.1 to 10wt.-%, based on the weight of the ether and second polymer, of at leastone component which enhances the compatibility of the ether of a) andthe polymer of b), said component comprising hydroquinone having asubstitutient, wherein the substituent is selected from the groupconsisting of alkyl, alkenyl, alkoxy, alkanoyl, alkylthio,alkylthioalkyl, alkyl amide, alkylamidealkyl, alkyl hydroxy, alkylcarboxyl, having from 1 to about at least 20 carbon atoms; or alkylaryl,arylalkyl, alkylsuphinyl, alkoxyalkyl, alkylsulphonyl, alkoxycarbonyl,wherein the alkyl or alkoxy has up to 20 carbon atoms, or the alkylsubstituent is a branched tertiary alkyl having a carbon chain of from 1to about 20 carbon atoms, or the substituent contains a polar group or ahalogen.
 12. The process of claim 11 wherein the components are blendedtogether at a temperature of from 200 to 270° C.
 13. The process ofclaim 12 wherein the temperature is from 200 to about 250° C.